Puffer-type electric switch

ABSTRACT

An electric switch comprises a movable contact and a blast cylinder connected therewith and coacting with a relatively stationary blast piston. The blast piston is supported by a spring and is movable against the action of the spring into a final disconnect position.

[451 Aug. 13, 1974 6/1971 Frink et al. 200/148 A FOREIGN PATENTS OR APPLICATIONS 0/1938 Great Britain.................. 200/148 A ABSTRACT An electric switch comprises a movable contact and a piston is against the acct position.

4 Claims, 2 Drawing Figures Primary Examiner-Robert S. Macon Attorney, Agent, or Firm-Herbert L. Lerner blast cylinder connected therewith and coacting with a relatively stationary blast piston. The blast supported by a spring and is movable tion of the spring into a final disconne O United States Patent [191 Zuckler PUFFER-TYPE ELECTRIC SWITCH Karl Zuckler, Berlin, Germany Assignee: Siemens Aktiengesellschaft, Berlin &

Munchen, Germany Jan. 19, 1972 Appl. No.: 219,023

200/148 A, 200/150 G Int. Cl. H0111 33/70 Field of Search.................... 200/148 A, 150 G References Cited UNITED STATES PATENTS 10/1947 ZOO/148 A [75] Inventor:

22 Filed:

H/ /////n/// I PATENT Eu AUG 1 3 m4 simmz PUFFER-TYPE ELECTRIC SWITCH DESCRIPTION OF THE INVENTION The present invention relates to an electric switch.

German Published application No. 1,913,969 discloses an electric switch with a stationary contact, a movable contact and a blast cylinder which is rigidly connected to the movable contact and is pulled during disconnection across a stationary piston. The front side of the blast cylinder which faces the stationary contact forms a nozzle for the flow of gas which is set into operation by the pump device comprising the stationary piston and the blast cylinder. The movable contact of the switch is made hollow in a known manner and serves for the removal of the switch gas. The movable contact and the stationary contact comprise a sliding contact which is closed during one half of the contact stroke or travel. In this manner, a high switching capacity may be obtained since, after the flow of gas is released through the contact functioning as a nozzle, the gas pumped by the pumping device is compressed to almost double pressure. This is due to the ratio of the compression distance to the blasting distance. The gas flow thus almost reaches the velocity of sound.

An object of the invention is to provide an electric switch of the aforedescribed type of German Published application No. 1,913,969 which provides the precompression determined by the compression stroke by the sliding contact which is closed during half of the contact stroke with a shorter contact stroke and thus with a shorter compression time which basically determines the total switching period without reducing the movement of the contact following the compression, or during the blowing of the arc.

Another object of the invention is to provide an electric switch of the aforedescribed type which functions with efficiency, effectiveness and reliability.

To accomplish this, and in accordance with the invention, the blast piston is supported by a spring and is moved against the action of the blast cylinder into a final disconnect position.

In the switch of the invention, the pump device is quasi movable, since the otherwise stationary piston is taken along toward the end of the disconnecting movement by the movable contact. Therefore, the compression which insures a specific pressure of the quenching gas prior to galavanic separation of the contacts, is no longer rigidly coupled to the movement of the contact, relative to time and space. As a result, the precompression may be effected with a small stroke in a very short time and, if necessary, as compensation for the. precompression, with large cylinder and piston cross sections prior to galvanic separation, although the further contact movement is so rated that a normal zero passage will be reliably measured at an alternating current. Thus, the compression and the blasting or blowing distance or travel are no longer at a ratio of l l at the same compression, but, for example, at 0.5 l. The pressure obtained thereby is maintained during the stroke of the contact up to the final position of the disconnecting movement or is even increased, since the blast piston is moved against the action of the spring.

The blast piston is preferably a ring piston comprising two parts. To accomplish this, a preferably rotationsymmetrical spring arrangement between both parts is recommended. This would make a cogging of the piston impossible. It is also favorable that the movable part of the ring piston consists, at least in part, of insulating material if this can provide a beneficial effect for the electric field.

Prior to the movement of the blast piston, a compression ratio of at least 1.5 1 should be obtained with the switch of the present invention. At higher compression ratios, too, switches in accordance with the invention can provide gas flow speeds in the order'of magnitude of the velocity of sound.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, wherein:

FIGS. 1 and 2 are similar sectional views of part of an embodiment of the electric switch of the invention in two different phases thereof.

In the interest of simplicity, only the part of a circuit breaker or power switch which is important to the invention is illustrated. The illustrated circuit breaker may be rated at kV, for example. The insulation of the switching path against ground and the switch operation by means of a suitable drive is ensured in a known manner.

As shown in FIG. 1, a switching tube 3 which bridges a gap 4 between nozzle contacts 1 and 2 cooperates with the stationary contact 1. The stationary contact 1 is a hollow nozzle and is positioned opposite the second hollow nozzle 2 as a burn-off electrode. The coaction occurs during the switch ON or connected position of the switch shown in FIG. 1. The outside of the stationary contact 1 bears against the switching tube 3 in order to provide a contact rated for the nominal current of the switch. An insulating cap 7 is connected to the movable switching tube 3 via a concentrically extending tubular portion 6. The insulating cap 7 functions as the front side of a blast cylinder 8.

A blast or blow piston 10 is stationary in relation to the blast cylinder 8. The blast piston 10 represents a ring piston which concentrically encloses the switching tube 3 and comprises a part 11 which is rigidly affixed to the nozzles 1 and 2 and is therefore completely stationary. The blast piston 10 further comprises a part 12 which is resiliently supported by the part 11. A spring 13 between the piston parts 11 and 12 is constructed in rotation-symmetry. Several helical springs or spring combinations may be uniformly distributed around the periphery of the ring piston 10 to provide the spring 13.

The action of the spring 13 holds the piston part 12 in switch ON postion of FIG. 1 via a stop 14 at the piston part 11. The piston 10 has a cap-like part 16 comprising insulating material which is turned so far toward the stationary contact 1 that the gap 4 between the stationary contact and the electrode 2 is bridged. Rubber buffers are provided at the stop 14 and at a stop 15 which faces the cylinder 8. The rubber buffers function as shock absorbers.

To disconnect the switch or switch it OFF, as shown in FIG. 2, the switching tube 3 is moved together with the blast cylinder 8, away from the stationary contact 1. Sulphur hexafluoride is used as a quenching agent and is compressed in the interior of the cylinder 8. The degree of compression prior to the separation of the contacts is determined by the movable piston part 12. Following a stroke which amounts to less than half of the entire contact stroke, the sulphur hexafluoride within the cylinder 8 is primarily compressed in the area between the insulating cap 16 and the stationary contact 1. Thus, a precompression ratio of at least 2 1 may be obtained. This is the instant when the movable switching tube 3 leaves the stationary contact 1.

The movable piston part 12 is simultaneously moved by the blast cylinder 8 in the disconnecting direction. At a high quenching pressure which is determined only by the outflow, a flow of the quenching agent is provided during a long contact movement. The flow of the quenching agent lasts at least for one and one-half halfwaves of an alternating current to be disconnected. In the final disconnecting position, the movable piston part 12 is adjacent and abuts the stationary piston part 11 and the insulating cap 7 frees the space between the electrodes 1 and 2.

The aforedescribed switch has stationary and movable piston parts 11 and 12 which mutually support each other in resilient relation. A similar effect may be obtained by constructing the piston parts as flexible diaphragms or corrugated tubes.

The possibly biased springs 13 are preferably designed so that during the blasting or blowing phase, that is, after the passage of the compression path or distance, the best possible constant force is present. At the end of the contact, the springs may also function as absorption members which absorb the kinetic energy of the movable switch portions.

While the invention has been described by means of a specific example and in a specific embodiment, it

should not be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. Electric switch means having a precom'pression quenching means comprising a stationary contact and a movable contact, a blast cylinder rigidly connected to said movable contact, a relatively stationary blast piston, said blast cylinder being pulled during the disconnect movement across said relatively stationary blast piston thereby compressing quenching gas in said cylinder before the separation of said switch contacts and feeding it, following the galvanic separation of the contacts, into the switching path, said blast piston comprising two parts movable with respect to each other and cooperating in forming the effective piston surface, one of said portions being supported, opposite said other portion, by a spring and being moved by the blast cylinder against the action of the spring, into a final disconnect position.

2. The switch as claimed in claim 1, wherein the two blast piston portions are constructed as a ring piston and are disposed in concentric relation.

3. The switch as claimed in claim 1, wherein one portion of the blast piston consists, at least partially, of insulation material.

4. The switch as claimed in claim 1, wherein prior to the movement of the spring-loaded piston part, a compression ration of at least 1.5 l is attained. 

1. Electric switch means having a precompression quenching means comprising a stationary contact and a movable contact, a blast cylinder rigidly connected to said movable contact, a relatively stationary blast piston, said blast cylinder being pulled during the disconnect movement across said relatively stationary blast piston thereby compressing quenching gas in said cylinder before the separation of said switch contacts and feeding it, following the galvanic separation of the contacts, into the switching path, said blast piston comprising two parts movable with respect to each other and cooperating in forming the effective piston surface, one of said portions being supported, opposite said other portion, by a spring and being moved by the blast cylinder against the action of the spring, into a final disconnect position.
 2. The switch as claimed in claim 1, wherein the two blast piston portions are constructed as a ring piston and are disposed in concentric relation.
 3. The switch as claimed in claim 1, wherein one portion of the blast piston consists, at least partially, of insulation material.
 4. The switch as claimed in claim 1, wherein prior to the movement of the spring-loaded piston part, a compression ration of at least 1.5 : 1 is attained. 